There are currently a number of different standards for wireless communication networks. These standards can cover a variety of aspects of a wireless communication system, such as air interface and core network signaling. Typically, wireless communication networks that operate using different air interface standards also operate using different core network signaling. For example, Global System for Mobile communications (GSM)-based networks use a Time Division Multiple Access (TDMA) air interface and GSM mobile application part (MAP) for core network signaling, whereas most wireless networks that are commonly referred to as Code Division Multiple Access (CDMA)-based networks typically employ a CDMA air interface and International Standard-41 (IS-41) for core network signaling.
The different air interface and core network signaling of GSM-based and CDMA-based networks limits the ability of subscribers from one of these networks to operate on the other network. To address this issue the J-STD-038 standard has been developed by the Telecommunications Industry Association to provide roaming between networks that operate according to these two technologies. This standard provides an inter-working and interoperability function (IIF) that acts as a gateway between a GSM-based and CDMA-based network to interpret signaling messages of one protocol and convert the messages into the protocol of the other network. The IIF must be provisioned with basic subscriber information, such as International Mobile Subscriber Identity (IMSI), Mobile Identification Number (MIN), Electronic Serial Number (ESN), Terminal type, and Network Access Mode (non-GPRS, GPRS or both).